Android 學習記錄-調試輸出

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顯示消息提醒
Toast.makeText(getApplicationContext(), "默認Toast樣式",
    Toast.LENGTH_SHORT).show();
自定義位置toast
toast = Toast.makeText(getApplicationContext(),
    "自定義位置Toast", Toast.LENGTH_LONG);
  toast.setGravity(Gravity.CENTER, 0, 0);//定位置
   toast.show();//顯示

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chmod +x gradlew -  給權限
./gradlew assembleDebug -編譯成APK   apk文件在app/build/apk
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Log.v(this.toString(), "This is Verbose.");  什麼都輸出
Log.d(this.toString(), "This is Debug.");   僅僅輸出DEBUG調試信息
Log.i(this.toString(), "This is Information"); 提示信息 
Log.w(this.toString(), "This is Warnning."); 警告
Log.e(this.toString(), "This is Error."); 錯誤  

第一個字符串一般填來自哪裏，比如什麼類，第二個是什麼什麼信息。